The synthesis of hemolymph proteins by the larval midgut of an insect Calpodes ethlius (Lepidoptera:Hesperiidae)

Subba Reddy Palli, Michael Locke

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38 Scopus citations


Ligated tubes of Calpodes ethlius (Lepidoptera:Hesperiidae) larval midgut with normal (i.e. apical secretions into the lumen and basal into the hemocel or medium) or inverted orientation (i.e. apical secretions into the hemocoel or medium and basal into the lumen) were incubated in artificial hemolymph in the presence of [35S]methionine to investigate protein synthesis and vectorial secretion. The midgut synthesizes and secretes at least eight polypeptides basally and seven apically. The tissue also synthesizes many other polypeptides that are not released at either surface. Two dimensional analysis of proteins labeled in vitro and in vivo showed that (a) proteins synthesized in vitro are the same as those synthesized in vivo, (b) different proteins are secreted on apical and basal surfaces, (c) in vitro apical secretions are the same as in vivo luminal proteins, (d) at least two of the basal secretions can be demonstrated in the hemolymph labeled in vivo. Almost all basal secretions showed immunological similarity with hemolymph proteins as observed by immunoprecipitation and fluorography. Arylphorin is a main hemolymph protein synthesized by the midgut. Midgut arylphorin has been identified by its precipitation by antibodies to hemolymph arylphorin. We conclude that insect midgut has bi-directional secretion. Luminal proteins (presumably digestive enzymes and perhaps goblet cell luminal contents) are carried to the apical face. A different set of proteins are carried basally to the hemolymph.

Original languageEnglish
Pages (from-to)561-572
Number of pages12
JournalInsect Biochemistry
Issue number4
StatePublished - 1987

Bibliographical note

Funding Information:
Acknowledgements--We are grateful to L. Wilkie and H. Leung for technical help, to H. Kirk, H. Fife, P. Delhanty and S. Henderson for useful discussion and to Dr B. G. Atkinson and Dr J. E. Steele for helpful comments on the manuscript. The work was supported by Natural Science and Engineering Research Council grant A6607 to M.L.


  • Midgut
  • arylphorin
  • hemolymph
  • vectorial protein secretion


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