Halaby R, Zakeri Z, Lockshin R A
Department of Biology, Queens College and Graduate Center of City University of New York, Flushing 11367, USA.
Biochem Cell Biol. 1994 Nov-Dec;72(11-12):597-601. doi: 10.1139/o94-079.
The labial gland of Manduca sexta is a valuable system to study the mechanisms of programmed cell death since the death of the gland is nearly synchronous and, except for the anterior duct, involves all of the tissue. The gland degenerates in 5 days during pupation. Our previous work documents a drop in total protein synthesis as the gland degenerates. To evaluate potential causes of this altered protein synthesis, we monitored several parameters of metabolism in dying cells: levels of adenosine triphosphate to estimate the energy resources of the gland; reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide to assess mitochondrial respiration; levels of acid phosphatase to assay lysosomal enzyme activity; and concentrations of cyclic nucleotides and inositol triphosphate to monitor signaling. While protein synthesis fell precipitously on day 0, total adenosine triphosphate and mitochondrial respiration were unchanged until the cells underwent massive collapse on day 3. Lysosomal acid phosphatase increased during early metamorphosis, and ultimately the bulk of the cytoplasm was destroyed in autophagic vacuoles. Changes in the concentrations of second messengers were modest and late. The relationships between the metabolism and the collapse of the labial gland are under investigation.
烟草天蛾的唇腺是研究程序性细胞死亡机制的一个有价值的系统，因为腺体的死亡几乎是同步的，并且除了前导管外，涉及所有组织。在化蛹过程中，腺体会在5天内退化。我们之前的研究记录了随着腺体退化，总蛋白质合成量下降。为了评估这种蛋白质合成改变的潜在原因，我们监测了垂死细胞的几个代谢参数：三磷酸腺苷水平以估计腺体的能量资源；3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐的还原以评估线粒体呼吸作用；酸性磷酸酶水平以检测溶酶体酶活性；以及环核苷酸和肌醇三磷酸的浓度以监测信号传导。虽然在第0天蛋白质合成急剧下降，但直到第3天细胞大量崩溃之前，总三磷酸腺苷和线粒体呼吸作用都没有变化。溶酶体酸性磷酸酶在变态早期增加，最终大部分细胞质在自噬泡中被破坏。第二信使浓度的变化较小且较晚。唇腺代谢与崩溃之间的关系正在研究中。
