Nagle G T, Painter S D, Kelner K L, Blankenship J E
J Comp Physiol B. 1985;156(1):43-55. doi: 10.1007/BF00692925.
Endogenous peptides induce egg laying in the marine mollusc Aplysia in two ways: egg-laying hormone (ELH) from the neuroendocrine bag cells acts directly, causing the release of eggs from the ovotestis; peptides A and B from the atrial gland act indirectly, activating the bag cells to release ELH. Another atrial gland peptide (egg-releasing hormone; ERH) is a structural and functional hybrid of ELH and peptides A and B; it can act both directly and indirectly to induce egg laying. Atrial glands were incubated in a mixture of 3H-amino acids for 18 h, and the biosynthetically labelled peptides isolated using sequential Sephadex G-50 column chromatography and isoelectric focusing. Radiolabelled peaks were localized and bioassayed in intact animals. Bioactive peaks were then characterized functionally using two additional assays: egg laying in bag cell-less animals (ELH-like peptides) and in vitro induction of bag cell discharge (A- and B-like peptides). ERH-like molecules are active in both assays. Homogeneity of bioactive IEF peaks was assessed by SDS-PAGE. Sephadex G-50 gel filtration of biosynthetically labelled atrial gland extracts reveals two major peptide peaks. Peak D (apparent Mr 6,000) is strongly radiolabelled and contains most of the egg-laying activity, but has a low absorbance at 274 nm. Peak E (apparent Mr 3,500) is weakly labelled and contains a small proportion of the total egg-laying activity, but has a large absorbance at 274 nm. Isoelectric focusing of radiolabelled peptides in peak D reveals seven distinct ELH-like species (pI 5.5, 7.5, 8.5, 8.7, 8.9, 9.1, 9.4), and two peaks (pI 5.9, 8.1) that have both ELH-like and A-/B-like activity. The pI 8.1 peak may result from the comigration of peptide A with ERH or with an unidentified ELH-like peptide. It is not yet clear whether the pI 5.9 activity results from comigration of distinct peptides or from the presence of a previously uncharacterized ERH-like molecule. Isoelectric focusing of radiolabelled peptides in peak E reveals five distinct ELH-like species (pI 7.3, 8.5, 8.7, 9.1, 9.4), and one peak (pI 8.9) with both ELH-like and A-/B-like activity. The pI 8.9 peak may result from the comigration of an ELH-like peptide with peptide B. Three of the ELH-like peptides (pI 8.5, 8.9, 9.1) found in peak E are probably identical to the ELH-like peptides found at the same pI's in peak D.(ABSTRACT TRUNCATED AT 400 WORDS)
神经内分泌袋状细胞分泌的产卵激素（ELH）直接发挥作用，使卵子从卵精巢中释放出来；心房腺分泌的肽A和肽B则间接发挥作用，激活袋状细胞释放ELH。另一种心房腺肽（释卵激素；ERH）是ELH与肽A和肽B的结构和功能杂合体；它既能直接作用也能间接作用来诱导产卵。将心房腺置于含3H-氨基酸的混合物中孵育18小时，然后使用连续的Sephadex G-50柱色谱和等电聚焦法分离生物合成标记的肽。对放射性标记的峰进行定位并在完整动物中进行生物测定。然后使用另外两种测定方法对生物活性峰进行功能表征：在无袋状细胞的动物中产卵（ELH样肽）和体外诱导袋状细胞放电（A样和B样肽）。ERH样分子在这两种测定中均有活性。通过SDS-PAGE评估生物活性IEF峰的同质性。对生物合成标记的心房腺提取物进行Sephadex G-50凝胶过滤，显示出两个主要的肽峰。峰D（表观分子量6000）有强烈的放射性标记，包含大部分产卵活性，但在274nm处吸光度较低。峰E（表观分子量3500）放射性标记较弱，包含总产卵活性的一小部分，但在274nm处有较大吸光度。对峰D中放射性标记的肽进行等电聚焦，显示出7种不同的ELH样物质（pI 5.5、7.5、8.5、8.7、8.9、9.1、9.4），以及两个具有ELH样和A/B样活性的峰（pI 5.9、8.1）。pI 8.1峰可能是肽A与ERH或与一种未鉴定的ELH样肽共迁移的结果。目前尚不清楚pI 5.9活性是由不同肽的共迁移还是由一种先前未表征的ERH样分子的存在导致的。对峰E中放射性标记的肽进行等电聚焦，显示出5种不同的ELH样物质（pI 7.3、8.5、8.7、9.1、9.4），以及一个具有ELH样和A/B样活性的峰（pI 8.9）。pI 8.9峰可能是一种ELH样肽与肽B共迁移的结果。在峰E中发现的3种ELH样肽（pI 8.5、8.9、9.1）可能与在峰D中相同pI处发现的ELH样肽相同。（摘要截断于400字）
