Related Experiment Videos
Molecular cloning of mRNAs expressed specifically during spherulation of Physarum polycephalum
Abstract:
A cDNA library was constructed using the poly(A)+ RNA extracted from spherulating Physarum polycephalum microplasmodia. This library (740 clones) was screened by differential hybridization with 32P-labeled poly(A)+ RNA from growing plasmodia and developing spherules. The results showed that at least 30% of the clones corresponded to mRNAs expressed specifically in spherulating plasmodia. The 35 spherulation-specific cDNA clones giving the strongest hybridization signals were analysed. From this group, four different sequences complementary to very abundant mRNAs were identified. They each accounted for 1.5% of 4.5% of all the clones in the library and probably represented the most abundant spherulation-specific mRNAs. In addition, four less abundant mRNAs were identified from stage-specific clones giving weaker hybridization signals. These sequences represented individually between 0.3% and 0.7% of the clones in the library. Northern blots showed that these eight different sequences were absent from plasmodia and were most abundant 24-36 h after the induction of spherulation. Similar results were also obtained when spherulation was induced by the addition of a sublethal concentration of ferrous iron ions to the growth medium. Hybridization of the spherule-specific clones to Southern blots of genomic DNA suggested the presence of one copy for each gene.
Insights
Researchers identified specific messenger RNAs (mRNAs) crucial for the spherulation process in Physarum polycephalum. This discovery sheds light on the molecular mechanisms governing this developmental transition.
Area of Science:
- Molecular Biology
- Developmental Biology
- Mycology
Background:
- Physarum polycephalum undergoes a developmental transition from growing microplasmodia to quiescent spherules.
- Understanding the molecular basis of this differentiation process requires identifying stage-specific gene expression.
- Polyadenylated RNA (poly(A)+ RNA) serves as a template for protein synthesis and reflects active gene expression.
Purpose of the Study:
- To identify and characterize specific messenger RNAs (mRNAs) expressed during the spherulation of Physarum polycephalum.
- To investigate the abundance and timing of these spherulation-specific mRNAs.
- To determine the gene copy number for these identified sequences.
Main Methods:
- Construction of a complementary DNA (cDNA) library from poly(A)+ RNA of spherulating microplasmodia.
- Differential screening of the cDNA library using labeled poly(A)+ RNA from growing and spherulating stages.
- Northern blot analysis to confirm mRNA abundance and timing.
- Southern blot analysis to assess gene copy number.
Main Results:
- At least 30% of the cDNA clones were specific to the spherulation stage.
- Four abundant and four less abundant spherulation-specific mRNAs were identified.
- These eight mRNA sequences were absent in growing plasmodia and peaked 24-36 hours post-spherulation induction.
- Southern blot analysis indicated a single gene copy for each identified sequence.
Conclusions:
- Specific gene expression programs are activated during Physarum polycephalum spherulation.
- The identified cDNAs represent key transcripts involved in this developmental transition.
- The study provides a foundation for further research into the regulation of spherulation in this model organism.