Choi M K, Fahrbach S E
Department of Entomology, University of Illinois at Urbana-Champaign 61801.
Arch Insect Biochem Physiol. 1995;28(3):273-89. doi: 10.1002/arch.940280308.
Half of the neurons in the abdominal nervous system of the moth Manduca sexta die after adult eclosion. Two physiological signals regulate post-eclosion neuronal death in adult moths. The first is endocrine: a decline in blood ecdysteroids is necessary for the death of neurons in the segmental ganglia. The second signal, which is highly specific for a pair of motoneurons found at the posterior midline in each of the three unfused abdominal ganglia, originates in the nervous system. It is transmitted from the fused pterothoracic ganglion to abdominal ganglion A3 via the intersegmental connectives. To characterize the signal of neural origin, we have developed an in vitro bioassay for neuron-killing factors ("neurocidins"). Aqueous extracts of pterothoracic ganglia were prepared and applied to cultured ventral nerve cords. These extracts exhibited concentration-dependent effectiveness in killing motoneurons. The active component of the extract was heat-stable and protease-sensitive. Size fractionation studies suggested that the active component has a molecular mass between 10 and 30 kD. This is the first report of an endogenous neuron-killing protein from an insect nervous system.
烟草天蛾成虫羽化后，其腹部神经系统中有一半的神经元会死亡。两种生理信号调节成年蛾羽化后神经元的死亡。第一个是内分泌信号：血淋巴蜕皮甾类激素的下降是节段神经节中神经元死亡所必需的。第二个信号起源于神经系统，对三个未融合的腹部神经节中每个神经节后中线处发现的一对运动神经元具有高度特异性。它通过节间连接从融合的翅胸神经节传递到腹部神经节A3。为了表征神经源性信号，我们开发了一种针对神经元杀伤因子（“神经毒素”）的体外生物测定法。制备了翅胸神经节的水提取物并将其应用于培养的腹神经索。这些提取物在杀死运动神经元方面表现出浓度依赖性效果。提取物的活性成分对热稳定且对蛋白酶敏感。尺寸分级研究表明，活性成分的分子量在10至30 kDa之间。这是关于昆虫神经系统中内源性神经元杀伤蛋白的首次报道。
