Cytolytic activity of Bacillus thuringiensis CryIC and CryIAc toxins to Spodoptera sp. midgut epithelial cells in vitro

Shainn Wei Wang, William J. McCarthy

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

A sensitive lactate dehydrogenase (LDH) assay was modified to determine the cytolytic activity of Bacillus thuringiensis CryIC and CryIAc delta endotoxins to viable collagenase-dissociated midgut epithelial cells (MEC) from larvae of Spodoptera frugiperda and Spodoptera exigua. The MEC preparations from these Spodoptera sp. consisted predominantly of columnar cells (65-75%) and goblet cells (25-35%). Time course microscopy experiments indicated that only the columnar cells became swollen during CryIC toxin incubation. Also, comparative cytotoxicity studies were run with cell lines of nonmidgut origin established from S. frugiperda (SF21AE) and S. exigua (SEUCR1A). Optimum conditions for the cytotoxicity assay were similar for MEC and cell lines of both species, and were met in an assay in which 0.1-ml cell concentrations (8.5 ± 0.5 x 104 cells) were incubated with toxin dilutions (0.01-20 μg) for 1 h at 24°C at a final pH of 7.8. The Spodoptera sp. MEC were twofold more sensitive to CryIC (68% lysis) than CryIAc (32% lysis) at optimum toxin levels (2.5-5 μg). Also, the SEUCR1A cells were more sensitive (2.3-fold) to CryIC (70% lysis) than CryIAc (30% lysis) at optimum toxin levels of 5-10 μg. The SF21AE cells, however, were twofold less sensitive to CryIC (30% lysis) than SEUCR1A cells and response to CryIAc and CryIC was similar. Immunoblot analysis of either Spodoptera sp. MEC or brush border membrane vesicles (BBMV) identified seven CryIC binding proteins with molecular mass of 137, 120, 115, 68, 65, 63, and 45 kDa. Occasionally, a 148- kDa protein hand was observed. The CryIAc toxin bound to two proteins on MEC and BBMV with molecular mass of 137 and 120 kDa.

Original languageEnglish
Pages (from-to)315-323
Number of pages9
JournalIn Vitro Cellular and Developmental Biology - Animal
Volume33
Issue number4
DOIs
Publication statusPublished - 1997 Apr

All Science Journal Classification (ASJC) codes

  • Developmental Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Cytolytic activity of Bacillus thuringiensis CryIC and CryIAc toxins to Spodoptera sp. midgut epithelial cells in vitro'. Together they form a unique fingerprint.

Cite this