In the larval midgut of Bombyx mori a K(+)-dependent transporter for leucine and amino acids with a hydrophobic side chain is responsible for the absorption of most essential amino acids. We investigated if a modulation of its activity occurred as a result of starvation or after hormonal treatments. We measured amino acid uptake in brush border membrane vesicles (BBMV) purified from the anterior-middle (AM) and posterior (P) regions of the midgut in fifth instar larvae. Silkworms were either starved or topically treated with low dosages of fenoxycarb, a molecule often used as a juvenile hormone mimic. The maximal uptake value of K(+)-driven leucine transport was increased in BBMV of AM- and P-midgut regions of starved larvae. The initial uptake rates of serine and glutamine, two amino acids transported by the same cotransporter as leucine, were also increased. Leucine kinetics proved that V(max) was the kinetic parameter modified by starvation in both midgut regions. Topical applications of fenoxycarb at a dose of 2.5 fg/larva immediately after the fourth ecdysis, induced an increase of leucine initial uptake rates and of intravesicular accumulation of leucine in both AM- and P-BBMV. Kinetic analysis of leucine uptake indicated again that V(max) was increased in BBMV from both midgut regions in treated larvae

Leonardi, M., Fiandra, L., Casartelli, M., Cappellozza, S., Giordana, B. (2001). Modulation of leucine absorption in the larval midgut of Bombyx mori (Lepidoptera, Bombycidae). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, MOLECULAR & INTEGRATIVE PHYSIOLOGY, 129(2-3), 665-672 [10.1016/S1095-6433(01)00330-0].

Modulation of leucine absorption in the larval midgut of Bombyx mori (Lepidoptera, Bombycidae)

Fiandra, L;
2001

Abstract

In the larval midgut of Bombyx mori a K(+)-dependent transporter for leucine and amino acids with a hydrophobic side chain is responsible for the absorption of most essential amino acids. We investigated if a modulation of its activity occurred as a result of starvation or after hormonal treatments. We measured amino acid uptake in brush border membrane vesicles (BBMV) purified from the anterior-middle (AM) and posterior (P) regions of the midgut in fifth instar larvae. Silkworms were either starved or topically treated with low dosages of fenoxycarb, a molecule often used as a juvenile hormone mimic. The maximal uptake value of K(+)-driven leucine transport was increased in BBMV of AM- and P-midgut regions of starved larvae. The initial uptake rates of serine and glutamine, two amino acids transported by the same cotransporter as leucine, were also increased. Leucine kinetics proved that V(max) was the kinetic parameter modified by starvation in both midgut regions. Topical applications of fenoxycarb at a dose of 2.5 fg/larva immediately after the fourth ecdysis, induced an increase of leucine initial uptake rates and of intravesicular accumulation of leucine in both AM- and P-BBMV. Kinetic analysis of leucine uptake indicated again that V(max) was increased in BBMV from both midgut regions in treated larvae
Articolo in rivista - Articolo scientifico
Animals; Bombyx; Carbamates; Insecticides; Larva; Leucine; Microvilli; Starvation; Time Factors; Intestinal Absorption; Phenylcarbamates
English
2001
129
2-3
665
672
none
Leonardi, M., Fiandra, L., Casartelli, M., Cappellozza, S., Giordana, B. (2001). Modulation of leucine absorption in the larval midgut of Bombyx mori (Lepidoptera, Bombycidae). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, MOLECULAR & INTEGRATIVE PHYSIOLOGY, 129(2-3), 665-672 [10.1016/S1095-6433(01)00330-0].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/218189
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