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FMRFamide‐like activity in the female locust during vitellogenesis
Author(s) -
Sevala V. M.,
Sevala V. L.,
Loughton B. G.
Publication year - 1993
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903370209
Subject(s) - fmrfamide , biology , suboesophageal ganglion , locust , hemolymph , vitellogenesis , medicine , hepatopancreas , staining , neuropeptide , endocrinology , axon , immunocytochemistry , migratory locust , acrididae , thoracic ganglia , anatomy , microbiology and biotechnology , ganglion , orthoptera , biochemistry , receptor , zoology , oocyte , botany , embryo , genetics
The control of oviposition in the locust involves the expulsion of eggs from the lateral oviducts, a process believed to be under neurohormonal control. In this paper we have attempted to identify this putative hormone. Immunohistochemical staining of the brain retrocerebral complex and suboesophageal ganglion of Locusta migratoria with antiserum against FMRFamide revealed a number of FMRFamide‐immunopositive cells. FMRFamide‐like immunoreactivity was present in median neurosecretory cells and lateral neurosecretory cells of the protocerebrum. Other FMRFamide‐immunoreactive cells were detected in the deutocerebrum and tritocerebrum. Immunoreactive cell processes were observed in the mushroom bodies, the central body, the optic lobes, and in the axon tracts leaving the pars intercerebralis and tritocerebrum. FMRFamide‐like material was also seen in the circumoesophageal commissures. Further FMRFamide‐like material was present in cell bodies of the suboesophageal ganglion. FMRFamide‐like staining activity changed dramatically during the oviposition cycle in mature adult females. The median neurosecretory cells stained lightly immediately after oviposition and remained pale until the third day, when staining of perikarya and axon tracts increased. The staining intensity decreased on days 4 and 5. The titre of FMRFamide‐like material in the hemolymph increased during the vitellogenic cycle but plummeted after oviposition. A single band of FMRFamide‐like material was evident on immunoblot following sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of adult female hemolymph. The approximate molecular weight of this molecule was 8,000. Gel permeation chromatography of hemolymph revealed a FMRFamide‐immunoreactive fraction with a molecular weight of 8,000. This fraction possessed myotropic activity when applied to the locust oviduct. It is argued that this molecule functions as an oviposition hormone in the locust.© 1993 Wiley‐Liss, Inc.