家蚕幼虫蜕皮过程体壁组织中的钙镁离子含量和磷脂酶C活性的变化

Variations of Calcium and Magnesium Ion Contents and Phospholipase C Activity in Integument of Molting Bombyx mori Larvae

采用原子吸收光谱法和酶联免疫法,测定与分析家蚕幼虫蜕皮过程体壁组织中的钙、镁离子含量和磷脂酶C（PLC）活力变化规律以及离子间的相互平衡现象等。各龄起蚕（蜕皮完成之时）体壁中的Ca2＋含量达至龄期的峰值,但随着龄期增加,这一峰值呈下降趋势,如3龄起蚕体壁中的Ca2＋质量比为8.281 5 mg/g,4龄起蚕为6.283 5 mg/g,5龄起蚕为5.133 5mg/g,并且在幼虫的其余生长时期,体壁中的Ca2＋含量总体上是小蚕期高于大蚕期。幼虫体壁中的Mg2＋含量在各龄蜕皮过程及随龄期的变化规律与Ca2＋大致相同,仅3龄起上升到较高值（0.612 3 mg/g）,在各龄蜕皮前有一次小幅震荡回升。幼虫体壁中PLC的活力在各龄眠前均达到最高值（38.2~41.0 U/mL）,并持续至眠中,随后逐渐下降到眠末低值区域（21.0~29.2U/mL）,在蜕皮完成后酶活力再次上升;5龄到预蛹期PLC活力都处于相对较低的水平。有趣的发现是：在幼虫每个龄期的蜕皮过程或其他生长时期,都有一个Ca2＋含量下降,而Mg2＋含量上升的反向变化时间段,且这一反向变化时间段随龄期增加向后推迟。

The changing regularity of calcium and magnesium ion contents and activity of phospholipase C（PLC） in integument of molting silkworm（Bombyx mori） larvae,and the mutual balance of ions were determined and analyzed by atomic absorption spectrometry（AAS） and enzyme-linked immune assay（ELISA）.Results indicated that Ca2＋ content reached peak value upon completion of molting in each instar.However,this peak value decreased with larval age.For example,Ca2＋ mass ratio in the newly exuviated larvae of the 3rd instar was 8.281 5 mg /g,while that of the 4th instar was 6.283 5 mg /g and that of the 5th instar was 5.133 5 mg /g.Moreover,Ca2 ＋content in integument of young larvae was generally higher than that of grown larvae.The similar trend of Mg2＋contents was found in different larval instars with the highest value（0.612 3 mg /g） detected only in newly exuviated larvae of the 3rd instar.Mg2＋ content had a small scale concussion rise before molting of each instar.The activity of PLC achieved peak value（38.2 to 41.0U /mL） before molting of each instar,sustained to the middle of molting,and fell down gradually to low values（21.0 to29.2 U/mL）.It increased again after completion of ecdysis.PLC activity was at relatively low level from the 5th instar tothe pre-pupa stage.Interestingly,an increasing of Mg2＋ content was found to coincide with the decreasing of Ca2＋ content in every instar,and the time point of coincidence was postponed with the development of silkworm larvae.