Submitted to: In Vitro Cellular And Developmental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 1999
Publication Date: N/A
Interpretive Summary: Heliothis virescens is a particularly noxious caterpillar, since it is very resistant to insecticides and often becomes established in vegetable and cotton fields after more susceptible pests, such as the boll weevil, have succumbed to standard treatments. Insecticides, toxins, and biological agents are usually sprayed or dusted on plants so that insects eat them with the plant material they ingest. The agents enter the digestive tract and thence pass into the general insect system. Therefore, it is important to study the physiology of the insect digestive tract in order to better understand how it develops, grows, and repairs injuries brought on by toxins and biological agents. This work is better done using cultures of digestive tract cells in the laboratory. However, we do not know how to grow these insect cells continuously and still retain the biological characteristics of digestive tract cells; the cultures live for only 3-4 months. As a partial remedy, we describe a method for freezing cultures of intestinal cells, alleviating the need for continuous preparation of new cultures. Frozen cells can also be supplied to scientists in need of midgut cells for studies of toxic agents. This information will be used by scientists.
Technical Abstract: Midgut cells from Heliothis virescens have been successfully cultured in vitro. Stem cells multiply in vitro, and daughter cells differentiate to columnar and goblet cells that are morphologically similar to those in the midgut in vivo. Columnar and goblet cells have finite life times, die, and are replaced by differentiating stem cells. Since only the stem cells are able to divide, they must be nourished by insect growth factors, as are vertebrate stem cells maintained in vitro. However, few insect growth factors are known, and we find it difficult to keep these primary cultures alive more than 3 or 4 months. In this paper we describe a method for freezing and later thawing cultures of H. virescens midgut cells, allowing continuous use of standardized cultures and reducing the need for constant preparation of new cultures.