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cDNA cloning and expression during development of Drosophila melanogaster MCM3, MCM6 and MCM7
1Laboratory of Cell Biology, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya 464-8681, Japan.
Abstract:
cDNAs encoding three Drosophila melanogaster MCM proteins, DmMCM3, DmMCM6 and DmMCM7, candidates of DNA replication-licensing factors, were cloned and sequenced. The deduced amino-acid sequences displayed 60, 59 and 68% identities with the respective Xenopus laevis homologues, XMCM3, XMCM6 and XMCM7. Six members of the D. melanogaster MCM family were found to share 31-36% identities in their amino-acid sequences, and to possess the five common domains carrying conserved amino-acid sequences as reported with X. laevis MCM proteins. DmMCM3, DmMCM6 and DmMCM7 genes were mapped to the 4F region on the X chromosome, the 6B region on the X chromosome and the 66E region on the third chromosome, respectively, by in situ hybridization. Contents of their mRNAs were proved to be high in unfertilized eggs and early embryos (0-4h after fertilization), then decrease gradually by the 12h time point, with only low levels detected at later stages of development except in adult females. This fluctuation pattern is similar to those of genes for proteins involved in DNA replication, such as DNA polymerase alpha and proliferating cell nuclear antigen, suggesting that expression of DmMCM genes is under the regulatory mechanism which regulates expression of other genes involved in DNA replication.
Insights
Researchers cloned and sequenced Drosophila melanogaster MCM3, MCM6, and MCM7 genes, key DNA replication factors. Their expression patterns in early development suggest regulation similar to other DNA replication genes.
Area of Science:
- Molecular Biology
- Developmental Biology
- Genetics
Background:
- DNA replication is a fundamental process crucial for cell division and organism development.
- MCM proteins are essential components of the pre-replication complex, playing a vital role in DNA replication licensing.
- Understanding MCM protein function in model organisms like Drosophila melanogaster provides insights into conserved eukaryotic mechanisms.
Purpose of the Study:
- To clone and characterize cDNAs encoding three Drosophila melanogaster MCM proteins: DmMCM3, DmMCM6, and DmMCM7.
- To analyze the sequence homology of these proteins with their Xenopus laevis counterparts.
- To investigate the expression patterns of DmMCM genes during Drosophila development and their potential regulatory mechanisms.
Main Methods:
- cDNA cloning and sequencing of DmMCM3, DmMCM6, and DmMCM7.
- Amino acid sequence alignment and homology analysis with Xenopus laevis MCM proteins.
- In situ hybridization for gene mapping of DmMCM3, DmMCM6, and DmMCM7.
- Quantitative analysis of DmMCM mRNA levels during different developmental stages.
Main Results:
- cDNAs for DmMCM3, DmMCM6, and DmMCM7 were successfully cloned and sequenced.
- High amino acid sequence identity (60-68%) was observed between DmMCM proteins and their Xenopus laevis homologues.
- Six Drosophila MCM family members shared 31-36% identity and conserved domains, indicating functional conservation.
- DmMCM genes were mapped to specific chromosomal locations (X chromosome and third chromosome).
- DmMCM mRNA levels were highest in unfertilized eggs and early embryos, decreasing significantly by later developmental stages, except in adult females.
Conclusions:
- The cloned DmMCM proteins are likely functional homologues of Xenopus MCM proteins involved in DNA replication licensing.
- The expression profile of DmMCM genes mirrors that of other DNA replication-related genes, suggesting coordinated regulation.
- These findings contribute to understanding the conserved mechanisms of DNA replication control in eukaryotes.