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The Venom Duct of Conus geographus: Some Biochemical and Histological Studies

The Bulletin of Philippine Biochemical Society
​Volume 2, Issue 1, 1979, Pages 30-51
​
Authors
Erlina S. Pali*, Oscar M. Tangco**and Lourdes J. Cruz*

*Dept. of Chemistry, College of Medicine, University of the Philippines - Manila
**Dept. of Anatomy, College of Medicine, University of the Philippines - Manila

Abstract
           The toxicity pattern and biochemical properties of the contents of successive sections of the venom ducts of Conus geographus were determined. Both lethal and paralytic activites were observed to increase towards the posterior duct region. In all segments, toxicity was found to be mainly associated with the soluble rather than the granular fraction. Data from SDS gel electrophoresis and thin layer gel chromatography suggest that the lethal activity of the venom is due mainly to the low molecular weight components found in the soluble fraction of the posterior segments.
        Histologic examination of the C. geographus venom duct reveals two types of granules: the smaller anterior granules which are eosin staining and the larger hematoxylin staining granules which occupy the middle to the posterior sections. Both types of granules are ellipsoidal in shape and appear to be enveloped by eosin staining sheath or membrane.
            Proteolytic activity was found to be higher in soluble fraction, with the activity being highest in the anterior region and decreasing toward the posterior end. Although the proteolytic activity of the granule extract from the anterior region is just slightly lower than that of the corresponding soluble fraction, no activity was found in granule extracts from the middle and posterior regions.
       Treatment of the residue (obtained after the extraction of the venom with buffer and 10% acetic acid) with elastase released toxic peptides from the granules. These peptides exhibited chemical and symptomatic properties similar to those exhibited by Conotoxins GI and GII.
         Based on the biochemical and histological data presented, the possible role of venom granules as storage packets for zymogens of digestive enzymes and precursors of the lethal components is discussed.

To cite this article
S.E. Pali, O.M. Tangco and L.J. Cruz, The Venom Duct of Conus geographus: Some Biochemical and Histological Studies, The Bulletin of Philippine Biochemical Society, Vol. 2, No. 1, 1979, pp. 30-51.     
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