Johnson L L, Norberg B, Willis M L, Zebroski H, Swanson P
Northwest Fisheries Science Center, NMFS, Seattle, Washington, 98112, USA.
Gen Comp Endocrinol. 1997 Feb;105(2):194-209. doi: 10.1006/gcen.1996.6821.
Somatolactin (SL), a recently identified teleost pituitary hormone which is a member of the growth hormone/prolactin family, was isolated from pituitary tissue of Atlantic halibut (Hippoglossus hippoglossus). Pituitary proteins were extracted in ammonium bicarbonate (pH 7.8), fractionated using gel filtration chromatography, and purified using reversed-phase high-performance liquid chromatography. Halibut SL was identified on the basis of molecular size (determined by gel electrophoresis and mass spectroscopy), cross-reactivity of the putative hormone with antisera to cod SL, and N-terminal amino acid sequence. Polyclonal antibodies to purified halibut SL were raised in rabbits, and a radioimmunoassay (RIA) was developed for measurement of plasma concentrations of SL using purified halibut SL as a standard. The RIA was tested in several flatfish species including Pacific halibut (Hippoglossus stenolepis), English sole (Pleuronectes vetulus), and rock sole (Lepidopsetta bilineata). The assay was specific for SL as indicated by absence of cross-reactivity with Atlantic halibut growth hormone, prolactin, and GTH alpha subunit. Dilutions of plasma and pituitary extracts from Pacific halibut, English sole, and rock sole were parallel to the Atlantic halibut SL standard curve, indicating that the assay is valid for a range of flatfish species. Using halibut SL antiserum, SL was localized in the pars intermedia of English sole pituitary, where it has been identified in previously examined teleost species. The RIA was used to measure plasma levels of SL in Atlantic halibut and English sole during reproductive development, and in English sole subjected to various types of environmental stressors, including handling and crowding. In both sole and halibut, plasma SL concentrations remained relatively constant throughout gonadal development, but dropped during or following ovulation. Plasma SL levels in English sole tended to increase in response to acute stress, in parallel with plasma cortisol levels.
生长抑素（SL）是最近在硬骨鱼中发现的一种垂体激素，属于生长激素/催乳素家族，它是从大西洋大比目鱼（Hippoglossus hippoglossus）的垂体组织中分离出来的。垂体蛋白用碳酸氢铵（pH 7.8）提取，通过凝胶过滤色谱法进行分离，并用反相高效液相色谱法进行纯化。根据分子大小（通过凝胶电泳和质谱测定）、假定激素与鳕鱼SL抗血清的交叉反应性以及N端氨基酸序列鉴定出大比目鱼SL。用纯化的大比目鱼SL作为标准品，在兔中制备了针对纯化的大比目鱼SL的多克隆抗体，并开发了一种放射免疫测定法（RIA）来测量血浆中SL的浓度。该RIA在几种比目鱼物种中进行了测试，包括太平洋大比目鱼（Hippoglossus stenolepis）、英国鲽（Pleuronectes vetulus）和岩鲽（Lepidopsetta bilineata）。该测定法对SL具有特异性，与大西洋大比目鱼生长激素、催乳素和促性腺激素α亚基无交叉反应。来自太平洋大比目鱼、英国鲽和岩鲽的血浆和垂体提取物的稀释液与大西洋大比目鱼SL标准曲线平行，表明该测定法对一系列比目鱼物种有效。使用大比目鱼SL抗血清，在英国鲽垂体的中间部定位到了SL，在之前检查过的硬骨鱼物种中也已鉴定出该物质。该RIA用于测量大西洋大比目鱼和英国鲽在生殖发育期间以及受到各种环境应激源（包括处理和拥挤）影响的英国鲽血浆中SL的水平。在鲽和大比目鱼中，血浆SL浓度在性腺发育过程中保持相对恒定，但在排卵期间或排卵后下降。英国鲽的血浆SL水平在急性应激反应中倾向于升高，与血浆皮质醇水平平行。
