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Developmental changes of FABP concentration, expression, and intracellular distribution in locust flight muscle
N H Haunerland1, X Chen, P Andolfatto
1Department of Biological Sciences, Simon Fraser University, Burnaby, B.C., Canada.
Abstract:
M-FABP from flight muscle of the locust, Schistocerca gregaria, is similar to mammalian H-FABP in its physical characteristics and amino acid sequence. We have studied developmental changes using ELISA, Northern Blotting, and EM/immuno-gold techniques. M-FABP is found in cytoplasm and nuclei, but not in mitochondria. It is the most abundant soluble muscle protein in fully developed adult locusts, comprising 18% of the total cytosolic protein. However, no FABP is detectable at the beginning of the adult stage. Its concentration rises dramatically during the next 10 days, after which it reaches its maximal value. Expression apparently is turned on after ecdysis and continues for 10 days; thereafter, FABP mRNA diminishes and reaches a constant, but low level, probably needed to maintain the current FABP level. From a series of experiments employing metamorphosis-controlling hormones and antihormones it is evident that the induction of FABP expression is directly linked to metamorphosis.
Insights
Locust muscle fatty acid-binding protein (M-FABP) expression is induced by metamorphosis, rising significantly after adult ecdysis. This protein becomes abundant in adult locusts, with its mRNA levels regulated post-induction.
Area of Science:
- Biochemistry
- Developmental Biology
- Insect Physiology
Background:
- Locust muscle fatty acid-binding protein (M-FABP) shares similarities with mammalian heart-type FABP (H-FABP).
- FABPs are involved in lipid metabolism and transport in various organisms.
Purpose of the Study:
- To investigate the developmental changes in M-FABP expression in the locust, Schistocerca gregaria.
- To determine the relationship between M-FABP induction and metamorphosis.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) for protein quantification.
- Northern Blotting for mRNA analysis.
- Electron microscopy (EM) with immuno-gold labeling for subcellular localization.
Main Results:
- M-FABP is localized in the cytoplasm and nuclei, but not mitochondria, of locust flight muscle cells.
- M-FABP is undetectable at the start of the adult stage, with levels dramatically increasing over the first 10 days post-ecdysis.
- FABP mRNA levels increase after ecdysis, then decrease to a maintenance level, suggesting post-transcriptional regulation.
Conclusions:
- M-FABP expression is directly induced by metamorphosis in locusts.
- The protein accumulates significantly during early adult development, becoming the most abundant soluble muscle protein.
- Hormonal regulation plays a key role in the metamorphic induction of M-FABP.