Abstract
The suboesophageal ganglion of the silkworm, Bombyx mori, is conceived to secrete two different hormones; diapause hormone (DH) for the silkworm and melanization and reddish coloration hormone (MRCH) for the common armyworm, Leucania separata. Whether or not these hormonal activities are derived from the same chemical entity was determined by comparing the activities of each hormone recovered from the sequential steps of purifications. By the solvent extraction of silkmoth heads, DH-A and MRCH were effectively partitioned into the same fraction. These two hormones behaved similarly on the column chromatographies with Sephadex LH-60, the first Merckogel OR 6000 and DEAE-Sepharose CL-6B. However, DH-A was clearly separated from MRCH in the subsequent purification steps such as the second Merckogel column chromatography or isoelectric forcusirig: As for another kind of DH, DH-B (the smaller in molecular size) was quite different from MRCH as well as DH-A in extractability and chromatographic behaviors. The highly purified sample of MRCH exhibited linear dose-response relationship in cuticular melanization of common armyworms.
The hormonal activities of DH-A and MRCH dropped down by the proteolytic digestions with trypsin, α-chymotrypsin or pronase P and, also by some physical or chemical, treatments. Interesting selective decrement of the two activities occurred only on MRCH by alkaline treatment with 0.1N NaOH and dansylation with DH-A activity unchanged.
Thus, it is concluded that MRCH is a peptidal hormone, whose chemical properties and structure (s) are not identical but is likely to be similar to those of DB-A.
