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Transcripts of one of two Drosophila cyclin genes become localized in pole cells during embryogenesis
W G Whitfield1, C González, E Sánchez-Herrero
1Cancer Research Campaign, Department of Biochemistry, Imperial College, London, UK.
Abstract:
Cyclins, originally discovered in the eggs of marine invertebrates, are proteins which undergo dramatic cycles of synthesis followed by degradation at the metaphase-anaphase transition of cell division. That they participate in the G2-M transition is supported by the fact that when synthetic cyclin messenger RNAs from clam and sea urchin are microinjected into the G2-arrested oocytes of Xenopus, they induce maturation. The cyclin of fission yeast is the product of the cdc13 gene, which is known to interact with cdc2, a gene required for the entry into mitosis. We have cloned the genes that encode A-type and B-type cyclins from Drosophila melanogaster by virtue of their sequence similarity to oligonucleotides corresponding to conserved regions of the cyclin genes. We show that both genes encode abundant maternal mRNAs, but whereas the cyclin A mRNA is relatively uniformly distributed before cell formation, the cyclin B mRNA becomes localized to the developing pole cells. In larvae, cyclin A is expressed predominantly in brain and imaginal disks, whereas cyclin B transcripts are abundant in testes.
Insights
Cyclins are proteins crucial for cell division. This study identifies and characterizes Drosophila melanogaster cyclin A and B genes, revealing their distinct maternal mRNA distribution and larval expression patterns.
Area of Science:
- Cell Biology
- Developmental Biology
- Genetics
Background:
- Cyclins are proteins regulating cell division, known for cycles of synthesis and degradation.
- Evidence suggests cyclins participate in the G2-M transition, inducing maturation when introduced into arrested oocytes.
- Fission yeast cyclin (cdc13 gene) interacts with cdc2, essential for mitotic entry.
Purpose of the Study:
- To clone genes encoding A-type and B-type cyclins from Drosophila melanogaster.
- To investigate the distribution and expression patterns of cyclin A and B mRNAs in Drosophila.
Main Methods:
- Cloning of cyclin genes based on sequence similarity to conserved regions.
- Analysis of maternal mRNA distribution in pre-cellularization embryos.
- Examination of larval expression patterns in specific tissues.
Main Results:
- Successfully cloned Drosophila melanogaster genes for A-type and B-type cyclins.
- Both cyclin A and B genes encode abundant maternal mRNAs.
- Cyclin A mRNA shows uniform distribution, while cyclin B mRNA localizes to pole cells.
- Larval expression: cyclin A in brain and imaginal disks, cyclin B in testes.
Conclusions:
- Drosophila melanogaster cyclin A and B genes are identified.
- Distinct spatial and temporal expression patterns of cyclin A and B mRNAs are revealed.
- These findings contribute to understanding cell cycle regulation and development in Drosophila.