Premium
Midgut electrophysiology of a small insect Orchesella cincta (L.): regional differences and influence of molting
Author(s) -
Van Kerkhove Emmy,
Klein Georg
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a351-a
Subject(s) - midgut , moulting , transepithelial potential difference , hemolymph , biophysics , chemistry , osmole , anatomy , electrophysiology , epithelium , medicine , biology , ion transporter , endocrinology , biochemistry , larva , membrane , ecology , genetics
Properties of the isolated midgut of the springtail are described for the first time. Effects of molting stage were assessed and/or of the location of the cells along the short length of the epithelium (about 1 to 1.5 mm). Hemolymph, cleared from hematocytes, was pooled (ca5μl from 200 individuals; 27±1.7SEMnl per individual, n=22). The samples were analyzed with a vapor pressure osmometer, ICP‐OES *, and micropotentiometry (Cl−.). pH was measured in situ in live animals with ion selective electrodes. The ionic composition in mM±SEM (Na + 154±2; K + 7.0±1.2; Ca ++ 9.8±3.5; Mg ++ 3.5±1.1 (n=3), Cl − 114±1 (n=11)), osmolality 296±1 mOsm (n=5), pH 7.3±0.1 (n=9) resembled that of other ancestral groups. The physiological solution mimicked this composition. Luminal perfusion and cable analysis of the isolated midgut was done. Under control conditions the basolateral membrane potential (V bl ) was −64±1mV (n = 51), the transepithelial potential (V te ) ‐ 11±1mV (n = 59) lumen negative. The apical potential (V ap ) was calculated to be −53mV, cell negative. The transepithelial resistance (R te ) was 389±35cm 2 (n = 69). Correlations between the electrical parameters, molting stage and location of the cells along the gut were tested with linear multiple regression. Near molting V bl became less negative (p=0.0006,n=22), V te and R te were not affected. V bl was less negative at the aboral side of the midgut (p=0.009,n=22). R te increased towards the aboral end (p<0.00001,n=57). The results show changes with molting and with progressive processing of food along the midgut.