Implications for the functions of the four known midgut differentiation factors: An immunohistologic study of Heliothis virescens midgut

Abstract

Antibodies to the peptides that induce differentiation of midgut larval stem cells, the midgut differentiating factors MDF-2, MDF-3, and MDF-4, bind to columnar cells in midgut cultures and in intact midgut of Heliothis virescens, in manners similar to the binding of anti- MDF-1 to those tissues. Antibodies to MDF-2 and MDF-3 also stained droplets in the midgut lumen, suggesting that columnar cells may also release MDF-2- and MDF-3-like cytokines to the lumen. Antibody to MDF-4 exhibited similar staining patterns but also recognized stem and differentiating cells, the presumed targets of peptides that regulate stem cell differentiation. Antibody to MDF-4 also bound to one type of endocrine cell in midgut cultures and in sections of midgut, as well as to the endocrine secretion released both to the midgut lumen and the hemolymph. Antibodies to the MDFs 1, 2, and 3, incubated with cultures of midgut cells, did not appear to prevent differentiation of the stem cells in the cultures but affected viability of mature cells, reflected in increased apoptosis and doubling of the number of differentiating cells compared to controls. Only antibody to MDF-4 induced temporary necrosis and inhibition of population recovery, indicating that MDF4 may be the true differentiation factor. The other MDFs may have additional functions beyond regulation of midgut stem cell differentiation in vivo.

Expression analyses of caspase‐1 and related activities in the midgut of Galleria mellonella during metamorphosis

“…MDF‐3 (with peptide EEVVKNAIA) has been extracted and chymotryptically digested from the haemolymph of Lymantria dispar pupae (Loeb & Jaffe, 2002). MDF‐3, together with other MDFs, namely, 1, 2, and 4, affected differentiation in stem cells isolated from larval midgut of H. virescens (Loeb et al ., 2004). We showed that this factor existed in cells in apical nidi and above.…”

“…All preparations were examined under a BX50 microscope (Olympus, Tokyo, Japan) equipped with Nomarski contrast, epifluorescence optics, and a charge‐coupled device camera. The specificity of anti‐MDF3 was examined by Loeb et al . (2004).…”

Densovirus Crosses the Insect Midgut by Transcytosis and Disturbs the Epithelial Barrier Function

“…Midgut stem cells from lepidopteran larvae can differentiate in vitro into the different midgut cell types (19,(25)(26)(27); the protocol set up by these authors was adapted to Spodoptera frugiperda. Within 2 weeks, the culture was composed of different morphologically identifiable cells (Fig.…”

Programmed cell death and stem cell differentiation are responsible for midgut replacement in Heliothis virescens during prepupal instar

“…Regenerative cell proliferation and differentiation in the insect midgut have been recently studied in vitro in order to understand the mechanisms that control stem cell proliferation and differentiation (Loeb et al , 2003(Loeb et al , 2004Ohlstein and Spradling 2006), but detailed in vivo analyses are scarce, even though differences in cell behavior between in vivo and in vitro systems have been detected (Baldwin and Hakim 1991;Loeb and Hakim 1996). In addition, some of these reports describe the involvement of mechanisms of programmed cell death (PCD) in the disappearance of the old midgut (Komuves et al 1985;Jiang et al 1997; Lee and Baehrecke 2001;Lee et al 2002;Uwo et al 2002;Wu et al 2006;Parthasarathy and Palli 2007).…”