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Changes in turbidity during microtubule assembly in brain extracts from normal chickens and chickens with muscular
Abstract:
When extracts of brain from normal and dystrophic chickens were incubated at 30 degrees C under conditions that favored microtubule assembly, the increase in turbidity of the extract from the dystrophic animal was approximately 50% less than the increase in the turbidity of the extract from the normal animal. In developmental studies using age-matched normal and dystrophic chickens this difference in turbidity was observed only with chickens 65 days ex-ovo or older. The extent of microtubule assembly, as determined by a sedimentation methodology, was a linear function of the total protein concentration in the extract and was equal in extracts from normal and dystrophic chickens. In contrast, the total increase in turbidity was much larger than could be accounted for by sedimenting microtubules and varied in a non-linear manner with the total protein concentration. There was no increase in turbidity when brain extracts that were prepared by centrifugation at 100,000 g X 40 min were incubated at 30 degrees C. The condensation reaction of the tubulin in these high speed extracts with microtubules was equal in the extracts from normal and dystrophic animals. These studies indicate that a developmentally regulated difference in brain extracts from normal and dystrophic chickens can be demonstrated by turbidimetric methods but this difference is unrelated to the formation of microtubules in these extracts. These studies support the concept that muscular dystrophy is also accompanied by a change in the central nervous system.
Insights
Brain extracts from older dystrophic chickens show reduced turbidity changes compared to normal chickens, unrelated to microtubule assembly. This suggests a central nervous system change accompanying muscular dystrophy.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Biology
Background:
- Muscular dystrophy is a genetic disorder primarily affecting skeletal muscle.
- Emerging evidence suggests potential central nervous system (CNS) involvement in muscular dystrophy.
- Microtubules are crucial cytoskeletal components involved in various cellular processes.
Purpose of the Study:
- To investigate potential differences in brain extracts between normal and dystrophic chickens.
- To determine if these differences relate to microtubule assembly.
- To explore the developmental regulation of these potential CNS changes.
Main Methods:
- Turbidimetric analysis of brain extracts from normal and dystrophic chickens at 30°C.
- Microtubule assembly assessment using sedimentation methodology.
- Developmental studies comparing age-matched chickens (≥65 days ex-ovo).
- Analysis of high-speed centrifuged brain extracts.
Main Results:
- Dystrophic chicken brain extracts showed ~50% less turbidity increase than normal extracts, specifically in older chickens (≥65 days ex-ovo).
- Microtubule assembly extent, measured by sedimentation, was comparable between normal and dystrophic extracts and linearly dependent on protein concentration.
- Turbidity increases exceeded those attributable to microtubule assembly and varied non-linearly with protein concentration.
- No turbidity increase was observed in high-speed centrifuged extracts, and tubulin condensation with microtubules was similar in both groups.
Conclusions:
- A developmentally regulated difference exists in chicken brain extracts, detectable by turbidimetry, but it is independent of microtubule assembly.
- These findings suggest a non-microtubule-related alteration in the dystrophic chicken brain.
- The study supports the hypothesis that muscular dystrophy is associated with concurrent changes in the central nervous system.