Hansen Heinz J M, Kelly Scott P, Grosell Martin, Wood Chris M
Risø National Laboratory, Roskilde, Denmark.
J Exp Zool. 2002 Dec 1;293(7):683-92. doi: 10.1002/jez.10166.
Cultured branchial cell epithelia from freshwater rainbow trout were incubated with ((32)P)phosphate and ((14)C)acetate as lipid precursors under both symmetrical (L15 media apical/L15 media basolateral) and asymmetrical (freshwater apical/L15 media basolateral) culture conditions. Epithelia composed of pavement cells alone, or containing both pavement cells and chloride cells, were examined. Lipids (labeled with (32)P and (14)C) were isolated and assayed by thinlayer chromatography, and fatty acids (labeled with (14)C) were isolated and assayed by paper chromatography. The main goal was to see whether the loss of a major incorporation into ((32)P)phosphatidylethanolamine [((32)P)PE], previously seen in eel gills in vivo when the fish were transferred from an osmotic steady state to more dilute media, was the result of a hormonal regulation, i.e., did it only apply to gill tissue in vivo or could it also be seen in the absence of hormonal modulation after incorporation of ((32)P)phosphate in vitro? We likewise wished to see whether a major incorporation into ((32)P)PE was dependent upon the presence of chloride cells. Results show that it is possible to obtain a ((32)P)PE dominated incorporation pattern, even in the pavement cells alone, provided that ((32)P)phosphate is added specifically to freshwater on the apical side of epithelia bathed asymmetrically (freshwater/L15). This is identical to the pattern seen in vivo in trout adapted to freshwater. However, this pattern is not seen under symmetrical conditions (L15/L15) or when ((32)P)phosphate is added to the basolateral media. The shift from symmetrical (L15/L15) to asymmetrical (freshwater/L15) culture conditions thus leads to the establishment of a major incorporation into ((32)P)PE and not to the equivalent loss as seen in vivo in more dilute apical media. We conclude that hormonal control is not needed to change the pattern of short-term lipid formation but, nevertheless, the responses are not altogether the same in vitro and in vivo. Furthermore, cultured trout gill epithelia, in contrast to gills in vivo, do not exhibit a marked incorporation of ((14)C)acetate into palmitoleic acid.
将淡水虹鳟的鳃细胞上皮组织在对称（L15培养基顶侧/L15培养基基底侧）和不对称（淡水顶侧/L15培养基基底侧）培养条件下，用（32）P磷酸盐和（14）C乙酸盐作为脂质前体进行孵育。对仅由扁平细胞组成或同时含有扁平细胞和氯细胞的上皮组织进行了检查。通过薄层层析分离并测定脂质（用（32）P和（14）C标记），通过纸层析分离并测定脂肪酸（用（14）C标记）。主要目的是确定先前在体内鳗鱼鳃中观察到的，当鱼从渗透稳态转移到更稀的介质中时，（32）P磷脂酰乙醇胺[（32）P PE]主要掺入量的减少是否是激素调节的结果，即它是否仅适用于体内的鳃组织，还是在体外掺入（32）P磷酸盐后在没有激素调节的情况下也能观察到？我们同样想确定（32）P PE的主要掺入是否依赖于氯细胞的存在。结果表明，即使仅在扁平细胞中，只要将（32）P磷酸盐专门添加到不对称培养（淡水/L15）的上皮组织顶侧的淡水中，就有可能获得以（32）P PE为主的掺入模式。这与适应淡水的鳟鱼体内观察到的模式相同。然而，在对称条件下（L15/L15）或当（32）P磷酸盐添加到基底侧培养基中时，未观察到这种模式。因此，从对称（L15/L15）到不对称（淡水/L15）培养条件的转变导致了（32）P PE的主要掺入的建立，而不是像在体内更稀的顶侧介质中看到的那样等量减少。我们得出结论，改变短期脂质形成模式不需要激素控制，然而，体外和体内的反应并不完全相同。此外，与体内鳃不同，培养的鳟鱼鳃上皮组织没有表现出（14）C乙酸盐显著掺入棕榈油酸。
